i'm salary and i have no overtime pay. sometimes we have to work late and possibly on sundays, but yet i'm not complaining. i knew it was going to be like this when i was interviewed and i'm fine with it.
(then again, this is my second day and i haven't really had to stay late or work weekends yet... this sunday, we shall see.)
regardless, if you're told the work is from 8-4:30 then you are obligated to report in for those hours. staying extra is up to you and is not required. if you go above and beyond, you may get nice bonuses, but it's definitely not a requirement. it's only a courtesy. some people let their job run their lives, other people let their lives run their jobs. it's your choice, and you don't have to hate yourself for working the requested hours. (i definitely wouldn't work late if i didn't have to -- unless i truly enjoyed what i was doing at the time)